<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
         /* CSS样式制作*/
    *{
    padding:0 ;
    margin: 0;
    }
    html, body{
    height: 100%;
    }
    .box{
    dispLay: fLex;
    height: 100%;
    }
    .box1,.box3{
    width: 208px;
    background-color: grey;
    }
    .box2{
    fLex: 1;
    background-coLor: yeLLow;
    }
    </style>
</head>
<body>
    <!-- HTML页面布局-->
    <div class="box">
    <div class="box1"></div>
    <div class="box2"></div>
    <div class="box3">
    </div>
</body>
</html>